Correcting typewriters have long been known which can remove incorrect characters and allow entry of correct ones by following an appropriate sequence of keystrokes (e.g., U.S. Pat. No. 3,780,846 entitled "Automatic Erasing Typewriter"and filed by Robert A. Kolpek et al, issuing on Oct. 9, 1973).
Subsequently, "Dictionary" typewriters have appeared on the market which contain a multi-word listing of correctly-spelled words stored in a read-only section of an electronic memory. An error detection unit emits a warning signal when an entered word does not compare with any word stored in the "dictionary" list. More powerful versions of these typewriters having an associated display unit provided search techniques (including statistically-governed types based on the nature of the typist's most frequently committed spelling errors) to find and display successive, properly-spelled "trial" words, one of these trial words then being selectable to replace the incorrect word.
Since that time, the market has likewise seen the advent of electronic typewriters with memories storing thesauri from which a typist can select one of a succession of synonyms and retrieve it for replacement of a word used imprecisely or in an erroneous context.
While the foregoing improvements did much to enhance the quality of communications prepared by poor spellers, dull writers, etc., there still has been the problem of determining over use of words without reliance on laborious manual counts or, conversely, without utilization of high-powered computer equipment, assuming the typewriter's system output was compatible with the input requirements of that equipment. This latter approach is achieved, however, with equivalent addition of considerable memory capacity devoted to programming and storage of the identified overused words. Thus, there is need for a simple, low-cost yet highly-efficient system discerning presence of overused words and providing information as to frequency of their use. In particular, it should be applicable to each differentiable word in edited text stored in the memory unit of electronic typewriters of the consumer type having limited display and memory capacity. Most importantly, the system should be adaptable with multiple use of existing memory and control elements, expansion of capacity with respect to these being minimized to the fullest extent possible.